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POTENTIAL MEDIA FOR MONITORING IN UTERO EXPOSURE TO 2,2’,4,4’-TETRABROMODIPHENYL ETHER
Citation:
RAYMER, J. H., W. STUDABAKER, L. C. MICHAEL, A. MURTHA, C. EMOND, AND L. S. BIRNBAUM. POTENTIAL MEDIA FOR MONITORING IN UTERO EXPOSURE TO 2,2’,4,4’-TETRABROMODIPHENYL ETHER. Presented at International Society of Exposure Analysis Annual Meeting, Durham, NC, October 14 - 18, 2007.
Impact/Purpose:
research presentation
Description:
There is evidence that many diseases are linked to environmental exposures early in life. Little is known about in utero exposures to most environmental chemicals. Polybrominated diphenyl ethers (PBDEs) are widespread in the environment as a result of many years of usage as flame retardants in commercial products. The development of an approach to estimating in utero exposure is needed to help link exposure with health outcomes. A physiologically-based pharmacokinetic model for 2,2',4,4'-tetrabromomodiphenyl ether (BDE-47), which included a fetal compartment, was developed for rats. Model output indicated that tissue concentrations were approaching equilibrium at GD-18 when daily oral dosing (1 mg/kg) was started on GD-8. Twenty four hours after the last dose, maternal fat had accumulated the greatest amount of BDE-47 and contained 35-48% of the total dose; blood contained 1.6-2.8 % of the dose. The fetus contained 0.4-1.9% of the dose with fetal blood and GI tract containing 0.01% and 0.01-0.04% of the total dose, respectively. The GI tract was considered a surrogate for meconium, a material that could be used readily as a medium for estimating in utero exposure in humans. Following IRB approval, 25 pregnant women were recruited and maternal blood was collected at a prenatal visit. Cord blood was collected at birth, meconium was collected shortly after birth, and breast milk was collected approximately 1 month after delivery. Concentrations of BDE-47 in human samples ranged from 0.5 to 18 ng/g lipid in cord blood, 0.04 to 28 ng/g lipid in meconium, and 0.02 to 3 ng/g lipid in breast milk. Relationships among the media and the potential utility of these media for measures of in utero exposure are being explored.